ac-power: follow-up for recent change

ac-power: follow-up for recent change

Follow-ups for 72586a971b5ee26b6681fc34ba43c0081dbd94da.

- drop 'Options' sections,
- drop underlining for link,
- fix indentation.

Prompted by https://github.com/systemd/systemd/pull/36850#discussion_r2020594171
> the underline stuff we only use for long --help texts that have sections,
> for the section headers. systemctl --help does that for example. This one
> here is not that long, hence doesn't really need section headers, and
> hence no underlining. The clickable links don't need to be explicitly
> underlined, the terminal emulators that supper hyperlinks will underline
> them on their own (for example gnome-terminal uses a dotted line).

Addresses https://github.com/systemd/systemd/pull/36873#discussion_r2017578611